The invention relates to a material as a starting material for the preparation of bone cement, a process for its preparation and a process for the preparation of bone cement.
In the surgery and orthopaedics of the locomotor system the replacement of a joint by an artificial joint has become a routine operation. The most common method here is to anchor metal prosthetic components in bone by means of a plastic mass which is also known as bone cement. The known bone cements are cold polymerizing two-component based plastics consisting of a monomer and a powdery polymer component in the form of spheres or granules. All the normal commercial bone cements are prepared with a polymethylmethacrylate (PMMA) base. Attempts to mix the two components of these bone cements have shown that homogeneity on the one hand and avoidance of bubbles on the other hand are the main problems in the mixing techniques of such two-component plastics. This is particularly the case when antibiotics are added, which is often difficult. In addition, the powder can create dust when shaken during the mixing process and contaminates the air. The powder can invade the respiratory system and indeed as far as the main bronchus, as experimental tests have shown. Furthermore, should mixing be performed under vacuum, the polymer powder is sucked up by the vacuum pump. The powder component is thus the essential obstacle for the preparation of the bone cement within a closed system which, on the other hand, would certinaly be welcomed from an industrial medicine point of view. Tests to evacuate the powder are incomplete to date in so far as it has not been possible in this way to guarantee a sufficient polymer sphere inclusion in the matrix of the bone cement. The incorporation of any filler particles, such as radiographic contrast agents or osteoinductive substances, presents even greater problems.
The object underlying the present invention is thus to overcome the above problems and to simplify the handling of the polymer powder during preparation of bone cement.